Flared or Trunicated Cones for Elevated Water Tanks. Specifically Sphere and Water Spheroids

Hello All. I am new to the group. I am looking for help in die design. My work involves fabricating elevated water tanks. We press or dish our elliptical heads involving segemented pie shaped plates. We use the typical male over female die configuration checking both raduis with radius boards as the piece is pressed.

Now to the problem. We have a Water Spheroid to fabricate that includes a flared or trunicated cone between the top of the cylinderical stem (support shaft)and the bottom of the spheroid tank itself.

The cone will be 10' diameter at its bottom and 15' diameter at it's top. The height of the cone will be 5'. The material is Mild Carbon A-36 and is 1.25" thick.

I just can't seem to get a three way die in my mind. I have used compound (two way) for decades. I have thought about rolling the pieces (blanks) to a larger than required radius and then press the curved pieces with a male die on bottom that would be retangular in shape and a female die on top to press the required radius at the bottom and opening the limit switch on the press to allow the die to form the curve to a larger diameter as I go.

I am hoping someone will reply and tell me what I am missing. I am not very confident in my idea. I appreciate any thoughts anyone has or any reference books for forming flared or trunicated cones.

I think you're going to need to do that forming in one pass, rather than two. If you try to do the rolling and then press the rolled segment into a flare, you're going to get buckling at the edges. Are you pressing these pieces cold or hot?

An alternative to pressing the compound curves is to do a compound rolling operation using shaped rolls and a programmable follower roll to control depth of engagement into the shaped rolls. I've done this with smaller non-ferrous pieces, but doing it on the scale you're discussing is out of my league by several orders of magnitude. So I'm just tossing out ideas here in the hope that they spark an insight on your part. :-)

Stephen Fitz-Gerald
Herman,
I must be missing something here or confused about what your asking...
A sketch would clarify allot I guess.
But if I was going to make such a cone I wouldn't use a die at all. I would cut (at least) 8 identical pie shaped pieces and have them BUMPED on a press brake.
Bumping will allow the pie shapes to be formed with different radii on either end,one radius to accommodate the 10ft diameter and the other radius to accommodate the 15ft diameter.Then these 8 identical parts are welded together to make the completed cone.

I am having trouble uploading a working drawing with diminsions. Do you have an email I could send it to.

Here is my new post.

We use these in elevated water tanks for municipalities for their drinking water supply.

The cone is a smooth or flared transition between the stem of the tank and the sphere. The tank is similar to a golf ball on a tee. It is known as a water sphere type tank. The flared cone goes between the shaft or stem of the tank and the sphere on top.

I have attached a drawing of the development of the double curved cone. The thickness runs between .5 and 1.5 inches. The drawing has the dimensions.

We have been rolling the exterior radius (usually around 50 degrees) and using a rectangular male/female die with the parallel portion of the die forming the inside
radius of the cone and the longitudinal curve being formed at 50 degrees.

The parallel radius is equal to the lower or tightest radius of the cone. We loosen the
amount of pressing as we move from the tighter (smaller end) to the top (bigger end).

While this has proven successful, it is time consuming and does not make each piece 100% identical. This requires additional fit up time to make the finished product within tolerance. We would like to make a die that would press the entire piece in one press. Our largest press is 750 Ton.

We use these in elevated water tanks for municipalities for their drinking water supply.

The cone is a smooth or flared transition between the stem of the tank and the sphere. The tank is similar to a golf ball on a tee. It is known as a water sphere type tank. The flared cone goes between the shaft or stem of the tank and the sphere on top.

I have attached a drawing of the development of the double curved cone. The thickness runs between .5 and 1.5 inches. The drawing has the dimensions.

We have been rolling the exterior radius (usually around 50 degrees) and using a rectangular male/female die with the parallel portion of the die forming the inside
radius of the cone and the longitudinal curve being formed at 50 degrees.

The parallel radius is equal to the lower or tightest radius of the cone. We loosen the
amount of pressing as we move from the tighter (smaller end) to the top (bigger end).

While this has proven successful, it is time consuming and does not make each piece 100% identical. This requires additional fit up time to make the finished product within tolerance. We would like to make a die that would press the entire piece in one press. Our largest press is 750 Ton.

I can't seem to get the drawing to load. Do you have an email address I could send it to ?

So as I interpret it you are basically creating the top portion of a gigantic golf tee? Visualizing this on such a scale I can see where extreme accuracy would be pretty important! Assume that you make these parts in 15 sections... you'd have pieces which would be slightly over 2 feet wide at the narrow end and just over 3 feet wide at the large end. As a ragged guess maybe about 6 feet long before forming (depending on the amount of flare). Since these will be made in 1.25" thick material any large inaccuracies would result in a real nightmare for your welders! My guess is that you'll want to keep the amount of flare small as that will give more triangularity and greater strength. That leaves you with a shallower radius at the top (large end) of the segments and a slight back bend lengthwise. If it were me, (I assume you have HUGE presses to work with) I would form a single die set based on many cross sections cut at 90 degrees to the length and assemble them to also model the lengthwise curve, then I'd hot bend the sections in one (or two) pressings. I might consider profiling the edges with a double chamfer before bending to get a head start on the welding prep. It seems to me as if a free hand approach such as you are thinking of might be inaccurate enough to create the threat of mutiny among my welding crews! I'd spend more on the forming and hopefully save a bit on the welding process.

Thanks for the comments from all. I am thinking the bottom die (male) might be rectangular with a length wise radius to accommodate the longitudal radius and another radius (left to right)with a radius equal to the smaller end radius of the cone. The top die (female) would be an upside down horse shoe with the radius of the smaller end. I am thinking this would allow the pressing (750 Ton) would accomplish the outside radius up and down the cone while pressing the proper radius as I progress up the piece from the small end to the big end. I would appreciate any thoughts anyone has regarding my thought process. I may be way out there with this idea. Thanks, Herman

This will be a cone with a small diameter on the bottom and a larger one on top. It has to be dished for the proper radius but at the same time the back has to break and flare out creating a smooth transition.

The real difficulty for me is going from a compound curve (typical Sphere, elliptical, etc. head) to a three deminsional die.

I think the dies will end up perpindicular to one another. The bottom die will be two or three feet wide and two feet long. It will have the smalles radius from left to right and a radius for the longitudial curve running from the top to bottom of the longitudial or length. The top die will be concave and horse shoe in shape. The width of the shoe will be sufficeint to go around the large end and get a tighter radius as it goes up. Thus to decrese the radius the die can just be allowed to lengthen it's stroke. The die will also have a curve the other way (90 degrees) to insure the longitudial curve of the exterior of the taper of the exterior of the flare.

I would appreciate your or anyone's elses help with this plan. It's the best I have come up with thus far. Not even sure if it will work.

I have been thinking of using a rectangular bottom die (male) with 3 to 4 foot radius l to r and a longitudial radius equal to the exterior flared radius. The top die would be female and perpendicular to the bottom die. It would be 3 to 4 foot radius l to r with a longitudial radius equal to the bottom die. I would appreciate and thought, comments, etc. Thanks, HermaFlared Cone: Here are the pic's. Thanks, Hermann

Thank to all for comments. We ended up doing a 1/4 scale model. We rolled the 50 degree radius with plate rolls and then bumped the piece on an old C Punch Frame. We used our CNC cutting table for to obtain the left to right radius and hand ground the opposing radius. We pressed the entire lenth of the piece with a die that would move up and down to accomadate the radius we were seeking. While not perfect (yet), we pressed the piece to a very tight and acceptable radius. Next step is to make a fixture for our 750 Ton press to install a flat blank and press what we want in one pass. Would appreciate any comments.

I can't seem to get the file to upload. Do you have an email I can send it to ?

We use these in elevated water tanks for municipalities for their drinking water supply.

The cone is a smooth or flared transition between the stem of the tank and the sphere. The tank is similar to a golf ball on a tee. It is known as a water sphere type tank. The flared cone goes between the shaft or stem of the tank and the sphere on top.

I have attached a drawing of the development of the double curved cone. The thickness runs between .5 and 1.5 inches. The drawing has the dimensions.

We have been rolling the exterior radius (usually around 50 degrees) and using a rectangular male/female die with the parallel portion of the die forming the inside
radius of the cone and the longitudinal curve being formed at 50 degrees.

The parallel radius is equal to the lower or tightest radius of the cone. We loosen the
amount of pressing as we move from the tighter (smaller end) to the top (bigger end).

While this has proven successful, it is time consuming and does not make each piece 100% identical. This requires additional fit up time to make the finished product within tolerance. We would like to make a die that would press the entire piece in one press. Our largest press is 750 Ton.

Stephen Fitz-Gerald
Simply put,an anticlastic shape is like a saddle,curves in two dimensions generally perpendicular to each other.
You say you have a 750 ton press. This is MORE THAN ENOUGH PRESSURE to form your parts IF you have a precise die/dies.
My father who was a master sculptor and managed to make all kinds of VERY complicated shapes (in metal)in his long successful career used to say,
"with the right leverage ,you can move the earth".
Part of his art in engineering huge monolithic metal sculptures was to apply precisely the RIGHT amount of pressure in EXACTLY the right spot to get recalcitrant metal to conform to his will and vision,sometimes with heat,sometimes not. His analogy was that one must SEDUCE the form from the material rather than BLUDGEON it with force into submission...
I myself have had great success, when I need a specific die made that is beyond my capacity in a home shop,by researching what industrial facilities are in the general area for metal forming with MODERN equipment and co-opting these industrial processes for Artistic applications.I would suggest you contact you nearest TANK CAP MANUFACTURERE since they make similar shapes in hot forming large pieces in the sort of dimensional thickness you need.I have had positive results working with an outfit near Los angeles called ORANGE COUNTY METAL WORKS .They may have changed their name,this info is dated.

Here is the latest. I can't seem to upload my drawing with diminsions. Do you have an email I could send it to ?

Here is my new post.

We use these in elevated water tanks for municipalities for their drinking water supply.

The cone is a smooth or flared transition between the stem of the tank and the sphere. The tank is similar to a golf ball on a tee. It is known as a water sphere type tank. The flared cone goes between the shaft or stem of the tank and the sphere on top.

I have attached a drawing of the development of the double curved cone. The thickness runs between .5 and 1.5 inches. The drawing has the dimensions.

We have been rolling the exterior radius (usually around 50 degrees) and using a rectangular male/female die with the parallel portion of the die forming the inside
radius of the cone and the longitudinal curve being formed at 50 degrees.

The parallel radius is equal to the lower or tightest radius of the cone. We loosen the
amount of pressing as we move from the tighter (smaller end) to the top (bigger end).

While this has proven successful, it is time consuming and does not make each piece 100% identical. This requires additional fit up time to make the finished product within tolerance. We would like to make a die that would press the entire piece in one press. Our largest press is 750 Ton.

Two years ago I posted an inquiry for ideas about how best to form a double curved cone.

We use these in elevated water tanks for municipalities for their drinking water supply.

The cone is a smooth or flared transition between the stem of the tank and the sphere. The tank is similar to a golf ball on a tee. It is known as a water sphere type tank. The flared cone goes between the shaft or stem of the tank and the sphere on top.

I have attached a drawing of the development of the double curved cone. The thickness runs between .5 and 1.5 inches. The drawing has the dimensions.

We have been rolling the exterior radius (usually around 50 degrees) and using a rectangular male/female die with the parallel portion of the die forming the inside
radius of the cone and the longitudinal curve being formed at 50 degrees.

The parallel radius is equal to the lower or tightest radius of the cone. We loosen the
amount of pressing as we move from the tighter (smaller end) to the top (bigger end).

While this has proven successful, it is time consuming and does not make each piece 100% identical. This requires additional fit up time to make the finished product within tolerance. We would like to make a die that would press the entire piece in one press. Our largest press is 750 Ton.